Timing attack on django-basic-auth-ip-whitelist

Impact

Potential timing attack exists on websites where the basic authentication is used or configured, i.e. BASIC_AUTH_LOGIN and BASIC_AUTH_PASSWORD is set. Currently the string comparison between configured credentials and the ones provided by users is performed through a character-by-character string comparison. This enables a possibility that attacker may time the time it takes the server to validate different usernames and password, and use this knowledge to work out the valid credentials. This attack is understood not to be realistic over the Internet. However, it may be achieved from within local networks where the website is hosted, e.g. from inside a data centre where a website’s server is located.

Sites protected by IP address whitelisting only are unaffected by this vulnerability.

Patches

This vulnerability has been fixed on version 0.3.4 of django-basic-auth-ip-whitelist. Update to version 0.3.4 as soon as possible and change basic authentication username and password configured on a Django project using this package.

Workarounds

Stop using basic authentication and use the IP whitelisting component only. It can be achieved by not setting BASIC_AUTH_LOGIN and BASIC_AUTH_PASSWORD in Django project settings.

References

• Django mailing list discussion

For more information

If you have any questions or comments about this advisory:

• Open an issue at https://github.com/tm-kn/django-basic-auth-ip-whitelist/issues
• Email us at the email specified on the security policy.

Acknowledgements

Thanks to Thibaud Colas for reporting this.